Lothair, Margrave of the Nordmark

Lothair (or Liuthar) (circa 940 – 25 January 1003) was a Saxon count and Margrave of the Northern March from about 983 until his death.

Born the eldest son of Count Lothair II of Walbeck and Matilda von Arneburg, he succeeded his father as Count Lothair III of Walbeck in 964. He was a paternal uncle of the chronicler Bishop Thietmar of Merseburg, son of his younger brother Siegfried. Lothair did not inherit the County of Walbeck, but rather became count in the Derlingau and Nordthüringgau of Eastphalia in 982. When his brother Siegfried died in 990, he tried to seize all his mother's possessions to the disadvantage of his nephews.

After Count Dietrich of Haldensleben in 983 had been deposed from the Northern March for failing to defend the bishoprics of Brandenburg and Havelberg east of the Elbe river in the Great Slav Rising, he was replaced by Lothair, who was first mentioned as margrave in 993. However, his attempts to wrest the eastern territories of the Northern March from the Slavic Lutici were unsuccessful and he actually ruled only over a small strip of land along the Elbe in the southwest. Lothair came into conflict with Margrave Eckard I of Meissen over the arranged marriage of his eldest son Werner with Eckard's daughter Liutgard, which the Meissen margrave opposed. He therefore put up resistance against Eckard's candidacy for the succession of late Emperor Otto III in 1002 and won the Saxon nobles over for the support of rivaling Duke Henry IV of Bavaria. Eckard was murdered in the same year, and the wedding of Werner and Liutgard could take place.

Margrave Lothair died in 1003 and was buried in Cologne. His widow, Godila of Rothenburg, remained unmarried for four years after his death. His first-born son Werner succeeded him in the Northern March and his second son, Count Lothair IV of Walbeck, eventually also placed a claim on it. His third son, Berthold, rebelled in 1017 and submitted in 1018, and his youngest son, Dietrich, became a canon at Magdeburg around 1008.